Effects of flash-boil shucking on biochemical, sensorial and ultrastructural properties of Yesso Scallop (Mizuhopecten yessoensis) adductor muscle during refrigeration

Scallop adductor muscle has great popularity for raw consumption in Japan, but conventionally shucking live scallops with high vitality by knife requires skill and is time-consuming. Flash-boil shucking is a convenient shucking method in sushi restaurants for live scallops. However, the effects of this treatment on the quality of its main edible part, the adductor muscle, are not clear. This study was conducted to investigate the impact of flash-boil shucking on the quality of raw-edible scallop adductor muscle, focusing on flavor-enhancing components and ultrastructure. Thermal treatment could contribute to the formation of flavor-enhancing nucleotides in the external layer of the adductor muscle. Adenosine monophosphate content increased with the boiling time, which significantly increased to 1.47 +/- 0.42 mu mol/g in the 30 s-boiled group compared with 0.38 +/- 0.13 mu mol/g in the control group (p<0.05). The rapid adenosine monophosphate accumulation after boiling resulted in a faster accumulation of inosine and hypoxanthine during subsequent refrigeration, which could bring bitterness to aquatic products. Flash-boil shucking had no discernible effect on the proportion of free amino acids relevant to the flavor of scallop adductor muscle, despite the possibility of a reduction in total free amino acids. The external layer of the scallop adductor muscle could be hardened after flash-boil shucking. At the ultrastructural level, muscle fibers tend to aggregate transversely and contract longitudinally depending on the heating time. Flash-boil shucking is ideal for consuming the raw-edible scallop adductor muscle promptly. Flash-boil shucking treatment is recommended for households, restaurants, and small factories for treating scallops with high vitality.